Stair climbing wheel chair



E. M; AYSTA STAIR CLIMBING WHEEL CHAIR June 29, 1965 4 Sheets-Sheet 1Filed Dec. '28; 1962 A i/[N702 fan/A20 M. Arsm 5% 4 flrraz/vfys June 29,1965 E. M; AYSTA STAIR CLIMBING WHEEL CHAIR 4 Sheets-Sheet 4 Filed Dec.2a, 1962 United States Patent 3,191,953 STAIR CLIMBING WHEEL CHAR EdwardM. Aysta, 124 6th St. S., Virginia, Minn. Filed Dec. 28, 1962, Ser. No.248,107 10 Claims. (Cl. 2805.22)

This invention relates to an invalid chair, Wheel chair, or similarconveyance, and in particular to vehicles of this type capable oftraversing uneven terrain and obstructions and which are capable ofpassing over curbs and ascending and descending stairs.

There has been a long standing need for an invalid chair or wheel chairwhich would increase the range of mobility of a handicapped individualbeyond that capable of being provided by conventional style chairs ofthis type. This need has been intensified of late by increased effortsto make handicapped individuals as selfsufiicient as possible and byefforts encouraging the employment of handicapped individuals. A greatdeal of effort has been expended and numerous types of wheel chairs havebeen devised in a search for a practical and workable wheel chair whichwould provide the range of mobility desired and which at the same timewould retain the conventional Wheel chairs versatility and convenienceand which would have maximum maneuverability, be safe and easy tooperate and which would be capable of being constructed at a reasonablecost to enable purchase thereof by a maximum number of the handicapped.Despite the ingenuity and effort which has been directed up to now tothe solution of this problem, no wheel chair has yet been developedwhich meets all of the desired requirements and which would'constitute apractical and workable design.

The type of wheel chair desired should enable the handicapped person tocope with the usual problems which he normally encounters in travelingto and from work or other places, and in moving about building interiorssuch as his own home or place of employment. One of the most importantproblems which must be met in this regards is to provide a chair capableof traversing street curbings and the like and capable of easily andsafely ascending and descending any stairways with average heightrise-rs and depth of tread as found in oflice buildings, homes andindustrial plants and the ascent and descent thereof should be able tobe performed without damaging the stair treads or the risers, andwithout requiring the assistance or presence of an attendant. Since thevehicle must perform the usual wheelchair functions most of the time,the chair provided with the aforementioned curb and stair traversingability should alsohave the versatility and convenience of conventionalwheel chairs. The wheel chair should be capable of being folded byactive handicapped persons in order to enable them to readily put themin automobiles and provide the handicapped wit-h the independentmobility desired. The chair must be strong enough to safely support theweight of the user and be capable of withstanding the rigors of use, andat the same time be sufii-ciently light in weight to enable the chair tobe easily folded, handled and lifted where necessary. The chair shouldalso be as narrow as possible to provide proper freedom of movement inbuildings and other structures for negotiating passage through narrowdoorways and the like. The chair should also have maximummaneuverability and the turning radius thereof should be as small aspossible. a

Any changes or adjustments required between normal travel and ascendingor descending travel should be capable of being accomplished in aminimal amount of time to eliminate unnecessary delays at streetcrossings, crowded stairway-s, etc. Vehicles driven or propelled by3,191,953 Patented June 29, 1965 ice the occupant should require aminimum amount of effort on the part of the occupant. Preferably, thevehicle should be capable of being conveniently propelled by an armstrength of ten pounds. The chair should also be so designed that thechair and the occupant are always in a proper state of balance and thechair should be fail safe to prevent uncontrolled descent thereof. Thechair should also be of reasonably inexpensive construction and shouldnot require the installation of special ramps, mechanical contrivancesor electrical outlets in buildings.

One object of this invention is to provide an invalid chair or wheelchair which meets all of the foregoing requirements and is superior todevices of this type previously developed and which constitutes apractical and workable solution to the problems long associated withvehicles of this type.

Another object is to provide novel means for readily converting aconventional wheel chair into a vehicle capable of traversing curbs,stai-rways and the like while retaining all of the desirable features ofsaid conventional chair and to provide a novel vehicle propulsion systemfor accomplishing same. 1

Another object is to provide a stair climbing wheel chair havingtraction wheels for normal travel and track or tread means fornegotiating curbs and stairways, and wherein the relative positions ofthe wheels and tracks can be selectively changed for selectiveinterchangeable engagement thereof with the chair supporting surface.

Another object is to provide a wheel chair of the type above describedin which the wheels are operatively disengaged from the tracks duringnormal travel and serve as the means for powering said tracks whentraversing stairways, and in which the seat structure automaticallyshifts between normal travel position and stair traversing positionsimultaneously with the change in relative posi- .tions of the wheelsand tracks.

Still another object is to provide a novel wheel chair which embodiestherein traction wheel means for normal travel and tread or track meansfor negotiating stair- Ways, curbing and the like, which wheels areretractable when the chair is to be used for stair climbing anddescending purposes and which While so retracted are capable offunctioning as the means for powering the tread or track means.

These and other objects and advantages of this invention will more fullyappear from the following description made in connection with theaccompanying drawings wherein like reference characters refer to thesame or similar parts throughout the several views,'and in which:

FIG. 1 is a side elevational View of a wheel chair embodying the presentinvention shown in normal traveling position with the near drive wheelomitted for clarity;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side elevational view of the chair of FIG. 1 with the neardrive wheel removed showing the relation of the several parts when saidchair is ascending a stairy;

FIG. 4 is a vertical half-section taken along the line 4-4 of FIG. 1;

FIG. 5 is a front elevational view of the chair when folded;

FIG. 6 is a detail view of the brake mechanism;

FIG. 7 is a sectional view on an enlarged scale of the track tighteningmechanism taken along the line 7-7 of FIG. 1;

FIG. 8 is a detailed elevational View on an enlarged scale of theratchet and pawl mechanism as seen along the line 8-8 of FIG. 1;

FIG. 9 is a detailed elevational view in partial section and on anenlarged scale of the seat latching mechanism; and

FIG. is a top plan view on an enlaged scale of the front cross-bracingunit.

The illustrated embodiment comprises a collapsible wheel chair havingsubstantially identical opposing traversely spaced apart side assembliesinterconnected by collapsible bracing and a tiltable, collapsible seatassembly mounted between the two side assemblies whereby the entirewheel chair assembly can be laterally collapsed and folded into compactform. Each side assembly includes a basic or main frame structure onwhich endless traction belt means, tracks or treads are mounted in fixedposition relative to their respective frames for supporting andpropelling the vehicle when ascending and descending stairways. The sideassemblies also include large manually operable traction drive wheelswhich are retractably mounted on the main frame structure whereby whenlowered they engage the ground and maintain the endless tracks above andout of engagement with the ground and the raising of which causeslowering of the tracks to a position whereby the tracks can serve as themeans for propelling the vehicle up and down the stairs. The sideassemblies also include drive or transmission systems connected to theirrespective track for powering same, and additional drive means connectedto, movable with and driven by the traction drive wheels, the additionaldrive means operatively and drivingly engaging said transmission systemswhen the wheels are raised and being disengaged from the transmissionsystems when the Wheels are in lowered ground engaging position. Thus,the drive wheels are drivingly connected to the tracks when the wheelsare raised, and are disconnected therefrom when lowered. The tiltingseat structure interposed between the side assemblies is linked to thetraction drive wheels in such fashion that the seat structureautomatically tilts to the desired position simultaneously with theraising or lowering of the wheels.

The illustrated embodiment also includes additional features, includingbrake mechanism for preventing uncontrolled descent of a stairway,releasable latch mechanism for maintaining the seat structure in fixedposition during normal use, and ratchet and pawl mechanism forpreventing slippage and reverse movement of the track drive and drivewheels while ascending a stairway, all of which are set forth in detailhereinafter.

Reference is now made to the accompanying drawings for a more detailedexplanation and better understanding of this invention. Since the sideassemblies are substantially identical in construction and arrangement,it is to be understood that a description of one applies to both, unlessotherwise indicated.

Considering the invention in more detail, each side assembly includesbasic integral frame structure which includes front and rear generallyvertically disposed members 10 and 11 respectively, the upper endportions of which are interconnected by longitudinally extending members12 which also serve as arm rests for the occupant. The lower endportions of the vertical members 10 and 11 are rigidly interconnected byelongate longitudinally extending lower frame members 13 which extendrearwardly of the rear vertical members 11 and the rear end portions ofwhich are bent or curved upwardly to facilitate the engagement of thechair with a stairway preparatory to ascending same in a mannerhereinafter described. Curved bracing members 14 extend between andinterconnect the vertical members 11 and the rearwardly extendingportions of the member 13. The frame members 10, 11, 12, 13 and 14 arepreferably formed of tubular, strong light weight metal to achievemaximum strength with minimum weight. The side assemblies also includeendless cleated tracks 15 capable of supporting the chair on a stairwayand propelling it thereover, which tracks are trained about forwardlydisposed drive pulleys 16 and a longitudinally arranged series of idlerpulleys 17, 18, 19

and'20. The drive pulleys 16 are rotatably mounted on the lower endportions of the front vertical frame members 10 by means of stub shafts16a. Idler pulleys 17 are connected to the frame structure by means ofelongate pulley supporting members 21 which have the idler pulleys 17rotatably mounted on the leading ends thereof by means of stub shafts17a. The rear ends of said pulley supporting members 21 are connected tothe lower frame members 13 by bolt fasteners 18a, which also serve asthe axles for pulleys 18. The intermediate portions of the supportingmembers 21 are supported by vertically disposed brackets 22 which arefastened to the rear vertical members 11 by means of U-bolts 23, thelower ends of said brackets being fastened to the pulley supportingmembers 21 by means of bolt fasteners 24. The idler pulleys 19 and 20are rotatably mounted on the lower frame members 13 by means of stubshafts 19a and 20a respectively.

To enable the tracks to be properly tensioned and tightened, the stubshafts 20a on which the rear idler pulleys 20 are mounted are slidablyseated in elongate slots 25 provided in the rear end portions of thelower members 13 and connected to block members 26 which are slidablyenclosed within the tubular members 13 (as best seen in FIG. 7).Adjusting bolts 26a are connected to said block members 26 and arehoused within the member 13 and protrude from the rear end thereof. Thebolts 26a are provided with nuts 27 which bear against the closed endsor caps 13a of the member 13 which provide seats for the nuts 27 wherebythe tension on the tracks can be adjusted as desired by loosening ortightening said nuts 27.

0 power and drive the endless tracks 15, chain drive or transmissionsystems are provided as follows. Small sprockets 28 are rotatablymounted on the rear frame members 11 by means of stub shafts 28a andlarger sprockets 29 are rotatably mounted on the front frame members 10by means of stud shafts 2901, said sprockets 28 and 29 being drivinglyinterconnected by endless sprocket chains 30 trained thereabout.Sprockets 31 which are smaller than sprockets 29 are connected tosprockets 29 and driven thereby and therewith and similar sprockets 32are connected to the drive pulleys 16 for driving same, said sprockets31 and 32 being drivingly interconnected by means of endless sprocketchains 33. These chain drive systems are driven in a manner hereinafterto be described.

Large conventional bicycle type traction drive wheels 34 capable ofbeing manually operated by the occupant of the wheel chair are providedon each side of the wheel chair as a part of each side assembly. Eachdrive wheel is retractably mounted on its respective frame by means ofan arm or lever 35, one end of which is pivotally connected to the rearframe member 11 by its being journaled on shaft 28a. The other end ofthe arm 35 carries an axle 36 on which the hub 34a of the wheel isjournaled. The hub has connected thereto an axle enclosing sleeve 37which constitutes an extension of the hub and on which is mounted adrive sprocket 38 which is rotatable with the sleeve 37 and driven bythe rotation of the drive wheel. The sprockets 38 are in planaralignment with their respective chains 30 so as to be operativelyengageable with the lower course thereof for driving same when the drivewheels are retracted and raised to stair climbing position. When innormal lowered position, the drive wheels 34 engage the chair supportingsurface and maintain the tracks 15 above and out of engagement with saidsurface to provide maximum mobility and maneuverability during normaluse. However, the connection of the drive wheels to the frame by meansof the arms 35 enables the drive wheels and arms to swing or pivot aboutthe axis 28a to a raised stair climbing position in which the drivewheels are preferably raised above the lowermost course of the tracks toenable the tracks to properly engage the stairs and propel the chairthereover. When the drive wheels are in this raised stair climbingposition, the drive sprockets 38 connected thereto are brought intodriving engagement with the chains whereby turning of the drive wheelsin this raised position effects powering of the tracks through themedium of the transmission system provided, and hereinbefore described.The gear ratio of the track drive mechanism may be varied as desired andis preferably such that a small amount of force (a minimum arm strengthof ten pounds) applied to the drive wheels will provide the powernecessary to propel the chair up a flight of stairs. The illustratedarrangement provides a preferred minimum ratio of 20 to 1 but it isapparent that this can be varied to meet any requirement.

The side assemblies are collapsibly interconnected by means of a pair ofcollapsible scissors type cross bracing units located forwardly andrearwardly of the chair. The front unit consists of a pair of elongatecrossed bracing members 39 and the rear unit consists of a similar pairof crossed bracing members 40, each of said pairs being pivotallyinterconnected as at 41. The lower ends of the bracing members 39 and 40are pivotally connected as at 42 to their respective front and rearvertical frame members 10 and 11. The upper ends of the front crossbraces 39 are pivotally connected to link members 43 as at 44, said linkmembers 43 being pivotally secured to the front vertical frame members10 as at 43a.

The upper ends of rear cross braces 40 are pivotally connected at 45a toone end of dog leg shaped link members 45, the other ends of said linksbeing secured to the rear vertical frame members 11 as at 45b. The linkmembers 43 are offset as at 43b (as best seen in FIG. 10), said offsetportions being adapted to engage the extreme upper end portions of thebraces 39 located above the pivot connections 44 when the wheel chair isunfolded (as best seen in FIG. 2) to limit the unfolding movement of thecross braces and hold them in the position desired. It will be notedthat the corresponding pivot connections 41 and 42 of the front and rearbracing units are co-axial as are the corresponding pivot connections44-45a and 4351-451) of these same units to insure correspondingmovement between said units.

The wheel chair assembly is additionally collapsibly supported andbraced by means of a pair of elongate bracing members 46 and 46', theouter ends of which are also pivotally connected to their respectivefront frame members at 46b, the inner ends of which are pivotallyinterconnected as at 47, one member 46 carrying a stop element 4a; forengaging the other member 46 and holding said member in the desiredhorizontal aligned unfolded position illustrated.

Thus, the entire wheel chair assembly can be collapsed into a compactfolded condition by simply raising members 46-46 out of alignment andpushing the side assemblies thereof towards each other and therebyfolding the cross braces 39-39, 40--40, and 46-46 and the entire chairassembly to the folded collapsed condition of FIG. 5.

The tiltable laterally collapsible seat assembly is disposed between theside assemblies and is designed to tilt relative to the basic supportingframe structure hereinbefore described simultaneously with the raisingor lowering of the drive wheels 34. This seat assembly includes a pairof generally vertically disposed transversely spaced back frame members48, and a back panel 49 of collapsible material extending between andconnected to said back members 48 to provide a back rest or support forthe occupant. The seat assembly also includes a pair of longitudinallyextending generally horizontal disposed laterally spaced apart elongateseat frame members 59, which are rigidly connected to their respectiveback frame members 48. A seat panel 51 of collapsible material extendsbetween and is connected to the seat members 50 to provide a seat forthe occupant. Said seat assembly also includes a pair of elongatedepending leg members 52, the upper ends of which are rigidly connectedto the seat frame members 50. The lower ends of the legs 52 have 6caster wheels 53 swivelly mounted thereon, which caster wheels engagethe ground or other supporting surface during normal use. These legmembers have mounted thereon a forwardly extending foot rest supportingmembers 54 on which are pivotally mounted suitable foot rests 55 whichare capable of being folded from a normal horizontal position to araised vertical collapsed position.

The back frame members 46 have handle bars 56 mounted thereon providedwith hand grips 57 to enable the wheel chair to be pushed and steered byan attendant where necessary or desirable. Thus, the seat assembly iscapable of collapsing laterally in response to the movement of the sideassemblies towards each other and folding of the wheel chair. The seatassembly is provided with braces 53 which rigidly interconnect the backand the seat frame members 48 and 50 respectively.

To tiltably connect the seat assembly to the basic frame structure, theforward end of the seat assembly is hinged to the main frame by means oflinks 59 which extend between and are pivotally connected to the legmembers 52 and the front vertical frame members 10 at 5% and 5%respectively. The intermediate portion of the seat assembly is hinged tothe frame by means of link members of? which extend between and arepivotally connected to the seat frame members 50 and the lower framemembers 13 at ila and dill) respectively. The rear portion of the chairis hingedly linked to the supporting frame by means of link members 61,the upper ends of which are ivotally connected to the rear end portionsof the seat frames 5%) at 61a, the lower ends of which are pivotallyconnected to the rear vertical frame member 11 at 61b. Side panels 62are provided which extend between and are connected to each pair offrame members 10 and 11 to partially enclose the sides of the chairassembly.

In order to accomplish simultaneous movement of the drive wheels and theseat assembly, elongate actuating levers 63 are provided, the lower endsof which are rigidly secured to the wheel arms 35 so as to be integraltherewith and constitute an extension thereof. The upper ends of thelevers 63 are connected to the seat back by a sliding connectionprovided by mounting brackets 64 secured to the back frame members 48and extending rearwardly thereof, said brackets having generallyvertically disposed slots 65 formed therein, said brackets and levers 63being slidably interconnected by means of bolts or pins 56 extendingtherebetween and slidably seated in the slots 65. The seat assembly andthe drive wheels 34 are linked together through the medium of the arms35 and levers 63 for simultaneous movement thereof relative to thesupporting frame structure. When the seat assembly is tilted rearwardly,the drive wheels simultaneously rise, and vice versa. To properlyposition the component parts of the wheel chair for ascending anddescending stairways, the occupant simply leans backward against theback of the seat assembly causing same to tilt rearwardly and maysimultaneously pull upwardly on the drive wheels, all of which causesthe seat assembly to tilt to the desired position to insure that theoccupant will be properly seated and balanced while on the stairway andraises the drive wheel to a retracted position to enable the tracks toproperly engage the stairs and places the drive wheels in drivingengagement with the drive system for the tracks whereby turning of thedrive wheels will propel the tracks in whichever direction desired.

The sprockets 38 are held in driving engagement with the chains 36 bythe weight of the occupant against the back of the seat assembly, whichengagement also limits the backward tilting of the seat assembly. Theleg 52 and links 43 are also designed and arranged that the legs 52 willengage the links 43 and be frictionally held thereby to limit thebackward tilting of the seat assembly past any undesirable position. Thetilting of the seat assembly is so arranged and controlled that theoccupant will be maintained in substantially the same position whentraversing a stairway as when in normal use.

The illustrated wheel chair has several additional other features whichimprove the efficiency, ease of operation or safety thereof. Forexample, elongate helically coiled counterbalancing springs 67 areprovided on each side which extend between and are connected at oppositeends to the links 60 and the front frame members 10 at oia and 67brespectively, which springs are tensioned by the tilting of the seatassembly and bias the seat assembly from tilted stair traversingposition to normal travel position to facilitate the return movementthereof.

Shock absorbing means for cushioning the return movement of the seatfrom tilted to normal position is provided by pneumatic piston andcylinder assemblies d8 similar to the conventional door check, thecylinders of which are pivotally connected to the links 60 at 63a, thepiston rods thereof being pivotally connectedto the front frame members10 at 6%. To prevent uncontrolled descent and make the wheel chair failsafe, brake arms 69 are provided on each side as a safety feature. Thesebrake arms are pivotally mounted on the lower frame members 13 by meansof Crosby clips 70, carried by said members 13, one leg 79a of saidclips serving as the pivot for the brake arms, the other leg 70b of saidclips serving as a stop for retaining and holding the brake arms in thedesired braking position, said other legs 70!) being adapted to beseated in recessed portions 69:: of the brake arms. The brake arms areyieldingly held in braking position against the stops 70b by means ofelongate helically coiled springs 71, the lower ends of which areattached to the upper ends of their respective brake arms above thepivot point thereof at 71a, the upper ends of the springs beingconnected to the curved frame members 14 at 71b. When raised, the lowerends of the brake arms are disposed above the lower course of the trackso as not to interfere with normal stair descent. When lowered, thelower end of the brake arms are positioned below the tracks so as toengage the stair tread and prevent further movement of the chair downthe stairs.

When ascending a stairway, the brake arms are maintained in loweredbraking position whereby if the wheel chair should start to slipdownwardly, the lower ends of the brake arms would engage the stairtreads and prevent further movement of the chair. However, as long asthe chair is properly moving upwardly on the stairway, the brake armswill not interfere with nor obstruct the upward movement of the wheelchair since the lower end portions of the brake arms below their pivotpoints will be pushed upwardly against the action of the springs 71 whenengaging the stairs in normal upward movement so as to pass freelythereover.

However, when descending the stairs, the brake arms must be maintainedin a releasable raised position until such time as they may be needed toavoid interference with the normal downward movement of the wheel chair.To accomplish this, brake control levers 72 are provided, the lower endsof which are pivotally connected on the side panels 62 at 72a. Stopmembers 73 are mounted on the panels 63 forwardly of the pivot 72a forengaging the leading edges of the control levers and limiting theforward movement thereof and maintaining the levers in a forwardposition in which the brake arms are in a raised position in which theydo not interfere with stair descending movement. Pulleys 74 are mountedon the control levers and cables 75 are trained thereabout, the lowerends of the cables being attached to the lower end portions of the brakearms below their pivots at 75a, the upper ends of the cables beinganchored to the panels 62 at 75b. Rear stop members 76 are mounted onthe panels 62 rearwardly of the pivot 72a of the brake control lever forengaging the control levers 72 and limiting the rearward movement of thecontrol lever and holding same in a brake release position.

The aforedescribed arrangement provides an over-center action for thebrake control levers 72. When the levers are pushed forwardly so as toengage and rest against the front stops 73, the lower ends of the cablesare pulled upwardly and pull with them the lower end portions of thebrake arms upwardly against the action of the springs 71 to a positionwhere it will not engage the stairs when the chair is descending same.To release the brake arms for stair engagement, the control levers '72are simply pulled or swung rearwardly so as to bring them intoengagement with the rear stop members 76. This movement shortens theeffective distance between the two ends of the cables and enables thebrake arms to be pulled downwardly into stair engaging and brakingposition through the biasing action of the springs 71.

To prevent undesirable slippage, back-up or lost motion of the drivewheels when ascending and descending stairs and also to preventuncontrolled movement of the track drive systems in the event that theoperator should let go of or lose control of the drive wheels, ratchetwheels '77 are also rotatably mounted on the stub shafts 28a and fixedlyconnected to the sprockets 28. Pawl members or arms 78 are pivotallymounted on the frame members 11 at 78a and are adapted to continuouslyengage the ratchet wheels 77 and permit free rotation thereof and thetrack system in one direction and prevent movement thereof and the tracksystem in the opposite direction in a manner well known when the wheelchair is ascending a stairway.

In the arrangement shown, it is apparent that to move the wheel chair upthe stairs, the drive wheels must be pushed forwardly or rotatedclockwise in FIGS. 1 and 3 to accomplish counter clockwise stairclimbing movement of the endless tracks. The ratchet and pawl mechanismsin the illustrated embodiment are designed to permit the drive wheels toturn freely in a clockwise direction when the wheel chair is ascending astairway, but prevents counter clockwise movement of the drive wheels.When the drive wheels are released, such as when the operator hasreached the end of a forward pushing movement on the drive wheels and ismoving his hands rearwardly so as to initiate another pushing movementon the drive wheel, the ratchet and pawl mechanism will hold the drivewheels against reverse counter clockwise movement and prevent slippagethereof until the operator has again firmly grasped the wheel to operatesame.

For descending the stairs and for normal travel over level surfaces, thedrive wheels must be free to rotate counter clockwise in the illustratedembodiment and for these purposes the pawls are simply swung upwardlyout of engagement with the ratchet wheels to permit free turning of thedrive wheels in either direction as desired. To hold the pawls out ofengagement with the ratchet wheels, spring latches 79 are mounted on thepanels 62 and have offsets 79a which engage and hold the pawls in raisedposition, the pawls being released for engagement with the ratchetwheels by pushing the latches 79 inwardly towards the panels 62.

Releasable latch mechanism is also provided to positively hold the seatassembly in a fixed forward position during normal use. In theillustrated embodiment, this latch mechanism comprises a latch member 80slidably mounted on the right hand front frame member 10 (as best seenin FIG. 9) for movement transversely of the seat assembly. The inner endof the latch member 80 is adapted to overlie and engage the right seatframe member 59 and hold the seat assembly in fixed forward position fornormal use. A helically coiled compression spring 81 is housed withinthe frame member 10 and encircles the reduced shank portion Stla of thelatch, which spring bears against the inner wall of the frame member 10and the shoulder 80b of the latch to continuously urge the latch memberinwardly and hold it in engagement with the seat frame member 50. Theouter end of the latch is provided with a shoulder 80c which engages theouter wall of the frame member 10 and limits the inward movement of thelatch and a handle 82 for operating said latch. The inner end of thelatch is beveled at 80d to permit the seat frame member 50 to bearthereagainst and push the latch outwardly to enable the frame member 50to move therepast and therebelow, the latch spring inwardly under theaction of the spring 81 when the frame member has passed therebelow tolock the seat assembly in forward position. To tilt the seat assemblybackwards, the occupant simply pulls the latch outwardly by pulling onthe handle 82 against the action of the spring 81 until the frame member50 is unlocked and the seat assembly is free to tilt.

Thus, for normal travel over level ground, the wheel chair assemblyappears as in FIG. 1, with the drive wheels 34 in lowered position andthe tracks raised to an outof-the-way position in which they do notengage the chair supporting surface. In such condition, the sprocket 38is disengaged from the chain 30, and there is no operative connectionbetween the drive wheels and the endless tracks. The seat assembly isheld in fixed forward position by the latch 80, and the pawls 78 are notengaged with the ratchet wheels 77, leaving the drive wheels free toturn in either direction whereby the wheel chair can be manuallypropelled and turned in the conventional manner by manipulation of thedrive wheels. The brake arms 69 during normal use are preferably held inraised position, but if left in lowered position will not interfere withmost normal usage, since when lowered they are above and out ofengagement with a normal level supporting surface.

To ascend a flight of stairs, the chair is backed up to the lowermoststair so that the rear upwardly inclined portions of the tracks can restagainst the lowermost stair. It will be noted that the tracks arenormally inclined from front to rear, not only to facilitate initialengagement with the lowermost stair preparatory to ascending same, butalso to have the tracks at an inclined attitude approximating the normalangle of inclination of the average stairway, thereby reducing thedegree of tilting movement required for the seat assembly to place it inthe properly balanced position desired for traversing a stairway. Thelatch mechanism between the seat assembly and the frame is then releasedand the drive wheels are free to retract and rise and the seat assemblyis free to tilt rearwardly, said retracting and tilting movement beingfacilitated by the occupant leaning backward against the chair structureand simultaneously lifting upwardly on the drive wheels, the tiltingmovement and rising of the drive wheels continuing until the sprockets38 are in positive driving engagement with the chains 30. The drivewheels rise sufificiently to enable the tracks to be lowered to stairengaging position whereby the tracks can serve as the means forpropelling the wheel chair over the stairs, and the forward end of thetracks are lowered into engagement with the ground or floor surfaceimmediately adjacent the lowermost stair whereby the entire wheel chairis supported by the tracks engagement with the ground surface and thelowermost stair immediately prior to beginning ascent thereof. The drivewheels are preferably raised (as illustrated) to a position where theyare located entirely above the lowermost courses of the tracks wherebythe drive wheels do not engage the stairs during travel thereover.

Also, it will be noted that as the seat assembly tilts rearwardly, thefront casters are also raised sufficiently so that they too will be in anon-interfering position for travel over the stairway. To complete thepreparation for stair ascent, the pawls are lowered into engagement withthe ratchet wheels and the brake arms are lowered to braking position.When the foregoing has been accomplished, the ascent of the stairs canbe take place by the occupants simply turning the drive Wheels, the turning thereof causing driving of the sprockets 38, which in turn power thetrack through the track chain drive system hereinbefore described. Thewheel chair during the ascent of a stairway appears as shown in FIG. 2.Upon reaching the top or bottom of a stairway, the chair components arereturned to their normal position as 1d illustrated in FIG. 1 by simplytilting the chair forwardly, lowering the drive wheels to groundengaging position and raising the tracks to inoperative position. Itwill be further appreciated that the rearward tilting of the chair forascending and descending stairways enables the occupant to be inproperly balanced state or condition at all times and thereby maintainsthe occupant in a safe and comfortable position at all times.

When ascending a stairway, the brake arms readily yield as they engagethe stair (as seen in FIG. 3), the forward end of the brake armsswinging upwardly against the action of the springs 71 to enable thebrake arms to freely pass over the stairs without interfering with themovement of the wheel chair thereover. However, should the wheel chairbegin to slip downwardly on the stairs, the lower ends of the brake armsengage the stair treads (as best seen in FIG. 6) and hold the wheelchair against further downward movement.

To descend a stairway, the drive wheels are retracted and the trackslowered at the top of the stairs, and the wheel chair is then movedforwardly and down the stairs by turning of the raised drive wheels in adirection opposite to that required for ascending movement. As the chairdescends the stairway, it appears as seen in FIG. 3, with the exceptionsthat the pawls are disengaged from the ratchet wheels and the brake armsare in the raised non-braking position of FIG. 1, with the brake controllevers 72 in forward position. If the wheel chair should slip or beginuncontrolled descent, the occupant simply pulls the brake control levers72 rearwardly, thereby releasing the brake arms for engagement with thestair treads in the manner hereinbefore described.

For storage or carrying in an automobile, the wheel chair can be easilyfolded and collapsed to the compact condition illustrated in FIG. 5 bysimply pushing the two side assemblies towards each other.

Although the embodiment of the invention herein illustrated anddescribed is of the manually operable type, it will be recognized thatthe wheel chair of this invention can be readily modified so as to bepower driven. It will also be apparent that presently availableconventional wheel chairs can be readily modified to incorporate thenovel aspects of this invention which enable the chair to be readily andinterchangeably used for both conventional level travel and for travelup and down stairs, over curbing and the like.

It will further be appreciated from the foregoing description that thewheel chair of this invention incorporates all of the features thereinconsidered desirable to give the handicapped the range of independentmobility desired, and yet retains all of the convenience and versatilityof a conventional wheel chair. Thus, the wheel chair of this inventioncan be readily converted for travel up and down stairs and for normallevel travel without undue delay or difficulty. It retains all of thehigh maneuverability of conventional wheel chairs and is capable ofturning in a minimum radius and is capable of being readily folded andcollapsed in the conventional manner into a compact package for storageand for carrying in automotive vehicles and the like. The chair isvirtually fail safe particularly as applied to its travel up and downstairs, and can be operated with a minimum of effort on the part of theoperator.

It will, of course, be understood that various changes may be made inthe form, details, arrangement and proportions of the various partswithout departing from the scope of my invention.

and a raised position, said vehicle being supported and propelled bysaid wheel means when said wheel means are in said lowered position,said track means being maintained in raised position above the lowermostportion of said wheel means when said wheel means are in said loweredposition, and disposed below the lowermost portion of said wheel meanswhen said wheel means are in raised position whereby said vehicle issupported and capable of being propelled by said track means for travelover a stairway, means interconnecting said chair structure and wheelmeans for simultaneous movement thereof whereby movement of said wheelmeans between lowered and raised position effects simultaneous tiltingmovement of said chair structure between a forward normal travelposition and a rearwardly tilted stair traveling position, first drivemeans drivingly connected to said track means for driving same, andsecond drive means for driving said first drive means, said second drivemeans being driven by said wheel means and swingable therewith wherebysaid second drive means drivingly engages said first drive means whensaid wheel means is in raised position and is disengaged therefrom whensaid wheel means is in lowered position.

2. A vehicle comprising a frame, endless track means mounted on saidframe structure in fixed position relative thereto, traction wheelsmounted on said frame structure for swinging movement relative theretobetween a lowered ground engaging position and a raised position, saidtracks being in engagement with the vehicle supporting surface when saidwheel are in said raised position, first drive means drivingly connectedto said track means for driving same, and second drive means for drivingsaid first drive means, said second drive means being driven by saidwheels and swingable therewith between said raised and loweredpositions, said second drive means when in said raised position beingdrivingly engaged with said first drive means whereby said tracks can bedriven by said wheels, said second drive means being moved out ofdriving engagement with said first drive means by the lowering of saidwheels to said lowered position.

3. A vehicle comprising frame structure, track means mounted on saidframe structure in fixed position, wheel means mounted on said framestructure and capable of movement between a lowered position in whichsaid wheel means engage the vehicle supporting surface and a raisedposition in which said track means are in engagement with saidsupporting surface, and chair structure supported by said framestructure and movable relative thereto between first and secondpositions, and means interconnecting said chair structure and wheelmeans whereby said chair structure is moved between said first andsecond positions by the movement of said wheel means between said raisedand lowered positions.

4. The vehicle of claim 3, including means for drivingly interconnectingsaid track and wheel means when said wheels are in raised positionwhereby said track means can be driven by said wheel means when saidtrack means are in engagement with the vehicle supporting surface.

5. A stair climbing wheel chair comprising laterally spaced apartopposed side frame structure, chair structure including integrallyconnected back, seat and leg portions disposed between said side framestructure and pivotally mounted thereon for tilting movement relativethereto between a forward normal travel position and a rearwardly tiltedstair climbing position, endless longitudinally extending track meansmounted on each of said side frame structures in fixed position relativethereto, said track means being upwardly and rearwardly inclined whensaid wheel chair is in condition for normal travel over a substantiallyhorizontal supporting surface, traction wheels pivotally mounted on eachof said side frames for swinging movement relative thereto between alowered vehicle supporting and propelling position and a raisedposition, said track means being maintained above the vehicle supportingsurface when said wheel means are in lowered position and capable ofsupporting and propelling the vehicle when said wheels are in raisedposition, means interconnecting said chair structure and said wheels forsimultaneous movement thereof whereby swinging movement of said wheelsbetween lowered and raised position effects simultaneous tiltingmovement of said chair structure between said forward and rearwardlytilted positions, first drive means drivingly connected to each of saidtrack means for driving same, and second drive means for driving saidfirst drive means, said second drive means being connected to and drivenby said wheels and swingable therewith whereby said second drive meansdrivingly engages said first drive means when said wheel means is inraised position whereby said track means can be driven by the turningmovement of said wheels, said second drive means being disengaged fromsaid first drive means when said wheels are in lowered position.

6. A stair climbing wheel chair comprising opposed laterally spacedapart side frames, chair structure including integrally connected back,seat and leg portions pivotally mounted on and between said side framesfor tilting movement relative thereto about a horizontal transverse axisbetween a forward normal travel position and a rearwardly tilted stairclimbing position, endless longitudinally extending track means mountedon said side frames in fixed position relative thereto, said track meansbeing upwardly and rearwardly inclined, a pair of traction wheels, andmeans for mounting said wheels on said side frames for swinging movementrelative thereto comprising an elongate arm, one end of which ispivotally mounted on said side frame, said wheel being rotatably mountedon the other end portion of said arm, said wheels being capable ofswinging movement relative to said side frame between a lowered groundengaging and vehicle supporting and propelling position and a raisedposition, said tracks being maintained in raised position above thewheel supporting surface when said wheels are in lowered position, saidtracks being lowered to ground engaging vehicle supporting andpropelling position by the raising of said wheel to said raisedposition, said arm being connected to said chair structure forsimultaneous movement of said wheels and aid chair structure wherebymovement of said wheels between lowered and raised position effectssimultaneous tilting movement of said chair structure between saidforward and rearwardly tilted positions, endless drive chain meanssupported by said side frames and drivingly connected to said trackmeans for driving same, and gear means carried by said arm and driven bysaid wheel, said gear means being adapted to drivingly engage saidendless chain means when said Wheel is in raised position whereby saidtracks can be driven by said wheels, said gear means being moved out ofengagement with said endless chain means by the lowering of said wheelsto said lowered position.

7. A stair climbing wheel chair comprising frame structure, track meansmounted on said frame structure in fixed position relative thereto,wheel means mounted on said frame structure and movable relative theretobetween a lowered ground engaging position and a raised position, saidtrack means being maintained in spaced relationship to the ground whenthe wheel means are in said lowered position and adapted to support saidwheel chair on a stairway and propel it thereover when the wheel meansare in raised position, and chair structure mounted on said frame fortilting movement relative thereto between a forward normal travelposition and a rearward stair traveling position and meansinterconnecting said chair structure and said wheel means forsimultaneous movement thereof whereby movement of said wheel meansbetween said lowered and raised positions effects simultaneous movementof said chair structure between said forward and rearward positions, theseat portion of said chair structure and said track means being inforwardly diverging relationship when said wheels are in loweredposition and in raised position, the angle of divergence being greaterwhen the wheel means are in raised position than when they are inlowered position.

8. A vehicle comprising a frame, chair structure mounted on said frame,endless track means and traction wheel means mounted on said frame, eachof said means being adapted to independently support said vehicle on andpropel it over a vehicle supporting surface, one of said means beingmovable relative to said frame and to said other means between twopositions, the other of said means being mounted in fixed positionrelative to said frame, said vehicle being supported by said track meanswhen said one means is in one of said positions, and supported by saidwheel means when said one means is in the other of saidpositions, saidchair structure being adapted for V movement relative to said framebetween two positions,

and means for moving said chair structure between said positionssimultaneously with and in response to the movements of said movablemeans.

9. A stair climbing wheel chair comprising laterally spaced apartopposed side frame structure, chair structure mounted between andsupported by said side frame structures, endless longitudinallyextending track means mounted on each of said side frame structures infixed position relative thereto, said track means being upwardly andrearwardly inclined when said wheel chair is in condition for normaltravel over the ground, traction wheels mounted on each of said sideframes for free movement relative thereto between a lowered vehiclesupporting and propelling position and a raised position, said trackmeans being maintained spaced from the ground when said wheel means arein lowered position and capable of supporting and propelling the vehicleon a stairway when said wheels are in raised position, said chairstructure being capable of tilting movement relative to its supportingside frame structure and said tracks, and means interconnecting saidchair structure and wheel means for simultaneous movement thereofwhereby movement of said wheel means between lowered and raised positioneffects simultaneous tilting movement of said chair structure betweenforward normal travel position and a rearwardly tilted stair travelingposition.

10. A stair climbing wheel chair comprising laterally spaced apartopposed side frame structure, chair structure mounted between andsupported by said side frame structures, endless longitudinallyextending track means mounted on each of said side frame structures infixed position relative thereto, said track means being upwardly andrearwardly inclined when said wheel chair is in condition for normaltravel over the ground, traction wheels mounted on each of said sideframes for free movement relative thereto between a lowered vehiclesupporting and propelling position and a raised position, said trackmeans being maintained spaced from the ground when said Wheel means arein lowered position and capable of supporting and propelling the vehicleon a stair way when said wheels are in raised position, said tractionwheels being pivotally mounted on each of said side frames for swingingmovement relative thereto between said raised and lowered positions,said chair structure being capable of tilting movement relative to itssupport ing side frame structure and said tracks, and meansinterconnecting said chair structure and wheel means for simultaneousmovement thereof whereby movement of said wheel means between loweredand raised position effects simultaneous tilting movement of said chairstructure between forward normal travel position and a rearwardly tiltedstair traveling position.

References Cited by the Examiner UNITED STATES PATENTS 2,902,101 9/59Cates 280-522 X 2,946,602 7/60 Lee 2802l1 3,111,331 11/63 Locke 280-522FOREIGN PATENTS 693,983 7/53 Great Britain.

OTHER REFERENCES Brochure: Wanted-A Stair Climbing Wheel Chair, January1962, National Inventors Council, US. Dept. of Commerce.

ARTHUR L. LA POINT, Primary Examiner.

2. A VEHICLE COMPRISING A FRAME, ENDLESS TRACK MEANS MOUNTED ON SAID FRAME STRUCTURE IN FIXED POSITION RELATIVE THERETO, TRACTION WHEELS MOUNTED ON SAID FRAME STRUCTURE FOR SWINGING MOVEMENT RELATIVE THERETO BETWEEN A LOWERED GROUND ENGAGING POSITION AND A RAISED POSITION, SAID TRACKS BEING IN ENGAGEMENT WITH THE VEHICLE SUPPORTING SURFACE WHEN SAID WHEELS ARE IN SAID RAISED POSITION, FIRST DRIVE MEANS DRIVINGLY CONNECTED TO SAID TRACK MEANS FOR DRIVING SAME, AND SECOND DRIVE MEANS FOR DRIVING SAID FIRST DRIVE MEANS, SAID SECOND DRIVE MEANS BEING DRIVEN BY SAID WHEELS AND SWINGABLE THEREWITH BETWEEN SAID RAISED AND LOWERED POSITIONS, SAID SECOND DRIVE MEANS WHEN IN SAID RAISED POSITION BEING DRIVINGLY ENGAGED WITH SAID FIRST DRIVE MEANS WHEREBY SAID TRACKS CAN BE DRIVEN BY SAID WHEELS, SAID SECOND DRIVE MEANS BEING MOVED OUT OF DRIVING ENGAGEMENT WITH SAID FIRST DRIVE MEANS BY THE LOWERING OF SAID WHEELS TO SAID LOWERED POSITION. 